Lead delivery apparatus

ABSTRACT

An apparatus for delivering a predetermined volume of lead to a mould includes a housing defining a lead reservoir having a lead outlet defined in its base and in communication with the reservoir. A runway is provided beneath the base, spaced from the base and generally parallel thereto. A block is provided slidably mounted between the base and the runway and defining a through cavity having the predetermined volume for receiving lead from the outlet in a first position and for releasing the lead in a second position. A mechanism is provided for reciprocating the block between the first and second positions. A cast on strap machine is also disclosed. A lead delivery apparatus comprising a delivery chute is also disclosed.

FIELD OF INVENTION

The present invention relates to an apparatus for delivery of apredetermined volume of lead to a mould and in particular, but notexclusively, to such apparatus for use in manufacturing cast on strapsduring the manufacture of batteries.

BACKGROUND OF INVENTION

In the manufacture of batteries, particularly for example lead acidbatteries, it is known to cast straps and other formations onto the lugsof battery plates so as to, for example, form a connection between a setof plates within a cell of the battery. Such straps are generally castby filling a mould cavity with lead and dipping lugs into the cavityprior to the cooling of the lead. Typically, the mould cavities arefilled by allowing lead to flow into channels at the sides of thecavities and spill over a weir into the mould. An example of such amoulding apparatus is shown in the Applicant's earlier applicationWO94/16466. In order to ensure a good connection between the lugs andcasting, the lead must remain hot until the lugs are in position.However, in order to minimise cycle time in production, the lead must becooled as quickly as possible once the plates are in position.

It is important that the volume of lead is carefully controlled duringstrap casting as excess lead (for example as a result of mould featuressuch as weirs) will have an impact on both the cost and weight of thefinal battery produced.

Embodiments of the invention seek to provide an apparatus which mayprovide consistent measuring of lead and/or provide delivery of leadwith minimal cooling during transit to the mould and/or enable unimpededaccess to the mould by the plates.

SUMMARY OF INVENTION

According to the first aspect of the present invention there is providedan apparatus for delivering a predetermined volume of lead to a mouldincluding:

-   -   a housing defining a lead reservoir having a lead outlet defined        in its base and in communication with the reservoir;    -   a runway beneath the base, spaced from the base and generally        parallel thereto;    -   a block slidably mounted between the base and the runway and        defining a through cavity having the predetermined volume for        receiving lead from the outlet in a first position and for        releasing the lead in a second position; and    -   a mechanism for reciprocating the block between the first and        second positions.

This apparatus enables a single controlled volume of lead to bedelivered accurately to an outlet location. In addition to ensuring aconsistent volume of lead being delivered to a mould, the apparatus mayalso ensure that the lead can be delivered from the reservoir withminimal heat loss.

The cavity may have an upper inlet which is aligned with the lead outletin the first position. The cavity may have a lower delivery port whichcan deliver lead in the second position. The cavity may be substantiallyceiling-less, for example, the upper inlet of the cavity may be sizedand shaped to match the lead outlet in the base of the housing.Alternatively, the cavity upper inlet may be smaller than the outlet inthe base of the housing such that it lies within the outlet in the firstposition. Such an arrangement has been found to ensure that dross doesnot form within the cavity of the block but will instead float up thetop of the reservoir from which it can be easily skimmed.

The runway may be provided with an opening at the second position.Alternatively, the runway may be arranged to stop short of the secondposition. The opening or runway end may be arranged to guide lead whichis released form the cavity.

The housing may define a bleed opening, which may be aligned in thesecond position for allowing the ingress of gas into the upper part ofthe cavity in the second position. Thus, advantageously the bleedopening assists with smooth delivery of the volume of lead when theblock is in the second position.

The block may further include a passageway, for example a through hole,for connecting the reservoir to a lead supply when the block is in thefirst position. The lead supply may, for example, be a constant headlead supply.

The apparatus may further comprise a drive mechanism for reciprocatingthe block. For example, the drive mechanism may comprise a crankmechanism.

The facing surfaces of the block and the reservoir may form a sealtherebetween. The facing surfaces of the block and the runway may form aseal therebetween. At least one of the, or each, pair of facing surfacesmay be provided with a graphite coating. The base of the housing and therunway may be arranged at an incline such that any lead leakage isdirected in a predetermined direction. A gully may be provided at theedge of the runway to contain any such leakage.

In some embodiments the lead may be released directly from the block atthe second position into a mould. Alternatively, the apparatus mayfurther comprise a chute defining a lead passageway for extendingbetween the second position and a mould fill position. A passageway maybe arranged to ensure that the turbulence of the flow of lead into themould is minimised and ensure a quick and clean fill of the mouldcavity. The passageway may include a channel and a gap at the mould fillposition and the chute may further comprise a wall on the opposite sideof the gap to the channel for directing lead downwards as it debouchesfrom the channel. The channel may be an open channel, for example a halfpipe channel.

The apparatus may further comprise a moveable support for supporting thechute and arranged to move the chute between a lead delivery positionand a rest or store position (for example, the moveable support may be acarriage).

The block may comprise a plurality of cavities. For example, a pluralityof cavities may be provided in which each cavity may be arranged todeliver a predetermined volume of lead to a different section of themould (for example to form different straps). The cavities may havedifferent volumes (for example one cavity may be for a strap and anothermay be for a strap including a post). Multiple cavities could be fedfrom a single reservoir. The reservoir may have a single lead outlet orcould be provided with a lead outlet for each cavity.

The runway may be provided with a blind hole which is aligned with acavity (and may, therefore, also be aligned with the inlet) when theblock is in the first position. The cavity may be sized and shaped tomatch the outlet of the cavity (such that the blind hole may coextensivewith the cavity when the block is in the first position). The blind holemay be arranged to provide a sump below the cavity for receiving lead.Advantageously, the Applicants have found that the provision of a sumphelps to resist the build up of dross on the sealing surface between therunway and block.

The housing may be provided with a cover to define an enclosed ullageabove the reservoir. Advantageously, the ullage may be filled with aninert gas which reduces or eliminates the formation of dross on thesurface of the lead. Therefore, the housing may further include an inletfor the provision of an inert gas to the ullage. The bleed opening maybe in communication with the ullage such that inert gas is drawn intothe cavity during delivery of the lead. Advantageously, this has beenfound to reduce build up of lead oxides on the walls of the cavity whichwould otherwise cause “decay” in the measured volume of the cavity.

A lead delivery apparatus may comprise a plurality of apparatusaccording to an embodiment of the invention. For example, a leaddelivery apparatus may comprise at least two blocks linked together toreciprocate together.

According to a further aspect of the invention, there is provided a caston strap machine including a mould comprising a mould block defining aplurality of mould recesses and an apparatus in accordance with anembodiment of the invention.

In some embodiments a block may be provided with a plurality of throughcavities each having a predetermined volume for receiving lead from anoutlet in a first position and for releasing the lead in a secondposition. For example, the cavities may each have a predetermined volumeto match that required for a particular mould recess.

According to a further embodiment of the invention, there is provided alead delivery apparatus comprising a delivery chute which, in use,defines a passageway between a lead delivery device and a mould whereinthe chute is moveable between a lead delivery position, in which atleast a portion of the chute is positioned over a mould, and a storeposition in which the chute does not overlie the mould.

The store position may be arranged to be below the plane of the uppermould surface.

The chute may be arranged to move across the surface of the mould beforebeing displaced in a direction which is substantially perpendicular tothe plane and the mould surface. For example, the chute may betranslated across the surface of the mould from the first position inwhich it is positioned over the mould to a second position in which thechute does not overlie the mould and may then further move in adirection which is substantially perpendicular to the plane and mouldsurface to reach the store position. Alternatively the chute may bemoved by a rotational movement.

At least part of the movement of the chute may be linked to the movementof a jig box which is arranged, in use, to bring a part into contactwith the lead in the mould. For example, the chute may move across thesurface of the mould before being moved below the level of the mould inconjunction with the movement of the jig box.

Whilst the invention has been described above, it extends to anyinventive combination of features set out above or in the followingdescription or drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments of the invention will now be described in detail byway of example only and with reference to the accompanying drawings inwhich:

FIG. 1 is a schematic cross-section view of a cast on strap machineaccording to an embodiment of the invention;

FIG. 2 is a schematic view of the embodiment of FIG. 1 in the reservoirand cavity fill position;

FIG. 3 is a schematic view of the embodiment of FIG. 1 in a leaddelivery position;

FIG. 4 is a schematic view of embodiment of FIG. 1 immediately afterlead delivery and with the chutes in their first retracted position;

FIG. 5 is a schematic view of the embodiment of FIG. 1 with the batteryplates brought into contact with the mould and the chutes in their fullyretracted position;

FIG. 6 is a schematic view of the embodiment of FIG. 1 as the straps areejected;

FIG. 7 is a schematic view of a mechanism for use in embodiments of theinvention; and

FIG. 8 is a schematic view of a multiple cavity block for use inembodiments of the invention.

DESCRIPTION OF AN EMBODIMENT

A cast on strap machine 1 in accordance with an embodiment of theinvention is arranged to provide liquid lead into the mould cavities ofa mould 50 before tabs 82 of a set of battery plates 80 are moved intoposition by a jig box 70 with the tabs 82 within the mould cavities andthe lead can solidify so as to form straps connecting the tabs. A leaddelivery apparatus 5 is provided for delivering a predetermined volumeof lead to the mould 50. The lead delivery apparatus 5 generallycomprises a housing 2, which defines an inlet reservoir 4, a block 10, amechanism 20, a runway 30 and a chute 40. The lead delivery apparatus 5is connected to a lead supply 60. It will be noted that in theillustrated embodiment a pair of identical lead delivery apparatus areprovided to deliver to opposing sides of the mould 50 (and fed from acommon lead supply 60). It will be appreciated that this will dependupon the type of mould to be formed and therefore the invention may beused in a single or multiple arrangements. For clarity, the followingdescription will describe the operation of only a single side of theapparatus but it will be appreciated from the figures that the two sidesoperate in an identical fashion (albeit with their motions mirrored).

The housing 2 defines a lead reservoir 4 in its interior and isgenerally arranged to have an open upper surface such that dross whichaccumulates maybe easily skimmed from the lead in the reservoir. Aninlet 8 is provided for the supply of lead and an outlet 6 is providedin the base of the reservoir.

The housing may further be provided with a cover 3 which encloses thereservoir 4 but which is spaced apart from the lead fill level of thereservoir. As such an ullage 4 b (i.e. an unfilled space) is definedabove the reservoir 4. A gas inlet 9 is provided at the rear of thehousing 4 which extends into the ullage 4 b such that, in use, theullage 4 b may be filled with an inert gas (for example pure nitrogen orargon). Typically, the gas will be introduced at atmospheric pressure(so as not to effect the flow of lead) but with a flow rate which issufficiently high to expel the air from the ullage 4 b.

The housing is further provided with a bleed opening 7 which (asdescribed in below) is arranged to be aligned with the through cavity 12when the block 10 is in the second position. The bleed opening 7 is influid communication with the ullage 4 b of the housing 2.

Spaced apart from, and below, the housing 2 is a runway 30 which isarranged parallel to the lower surface of the housing and defines a slottherebetween which is shaped and sized to receive a block 10. The runwayis provided with a through hole 34 aligned with the inlet 8 on thehousing 2 and a blind recess 36 in alignment with the outlet 6 of thehousing 2 (the blind recess 36 will form a sump as described below). Therunway 30 is sloped relative to the horizontal such that it's inward(i.e. closest to the mould 50) end is higher than its rearward end. Thisensures that any lead which escapes during operation of the machine willrun away from the mould 50. Adjacent to the rearward (and lowermost)point of the runway 30 there is provided a gully 39 (which may be formedas part of the runway 30 or the lead supply pipe 66 which is positionedbelow the runway) for catching any lead leakage. The gully may bearranged to return the lead to the lead supply 60.

The block 10 is provided with a through cavity 12 and a through hole 18.In the non-displaced position of the block 10 the through hole 18 isaligned with the inlet 8 and through hole 34 to form the inlet path tothe lead reservoir 4. In the same position, the through cavity 12 isaligned with the outlet 6 of the lead reservoir 4 and the blind hole 36of the runway 30 such that lead from the reservoir will enter the blindhole 36 and cavity 12.

The mechanism 20 comprises a crank mechanism attached to the block 10and arranged (as described below with reference to FIGS. 2 to 5) to movethe block between its neutral position and a lead delivery position.

A chute 40 is provided which defines a passageway 42 which, in use, isarranged to deliver lead from the block 10 to the mould 50. Thepassageway 42 defines an inclined pathway for the lead and is providedwith radiused corners to ensure smooth flow and minimise turbulence ofthe lead. The chute is provided with a moveable support 48 which isarranged to move the chute between a delivery position and a retractedposition (as will be described in more detail with reference to FIGS. 2to 5). A wall 44 is provided at the end of the chute 40 proximal to themould 50 and a gap 45 is provided between the passageway 42 and wall 44.The gap 45, thus, forms an outlet to the chute 40.

FIG. 2 shows the apparatus in its starting position in which the block10 is aligned such that the through cavity 12 is below the outlet 6 ofthe lead reservoir 4 and the through hole 18 is aligned with the inlet 8of the lead reservoir 4. Thus, lead will flow from the constant headlead supply 60 (as shown in FIG. 1) through supply pipes 66A and 66B(which may typically be heated) and hole 34 in the runway 30 into thereservoir 4. The reservoir will be maintained at a fill level defined bythe head of the lead supply 60 (which is defined by a weir 64). As thethrough cavity 12 is in fluid communication with the lead reservoir 4, apredetermined volume of lead will fill the cavity 12 and an additionalvolume of lead will enter the blind hole 36 so as to provide a sumpbelow the cavity 12. It will be noted that in this step the chutes 40are already in the delivery position in which the passageway 42 is belowthe end of the runway 32 and the gap 45 which defines the outlet of thechute is positioned above the mould recess of the mould 50.

To commence filling of the mould, the mechanism 20 is actuated to slideblock 10 relative to the housing 2 and runway 30, as shown by the arrowsA in FIG. 3. The actuation mechanism will be described in more detailwith reference to FIG. 7 below, but may be any convenient mechanismwhich provides a reciprocating action of the block 10. The block 10slides inwards towards the chute 40 until it reaches its second position(as shown in FIG. 3) in which the delivery port 16 of the through cavity12 is aligned with the end 32 of the runway 30. In this position thebleed opening 7 provided in the housing 2 is in fluid communication withthe inlet of the through cavity 12 such that gas may be drawn into theupper portion of the through cavity 12. This arrangement helps to avoidany vacuum effect which may hinder the release of the lead within thethrough cavity 12. Further, since the bleed opening 7 is in fluidcommunication with the ullage 4 b the gas drawn into the cavity is inertgas. Advantageously, this has been found to reduce or avoid theformation of lead oxides on the surfaces of the through cavity 12 whichwould otherwise (over the course of many cycles) reduce the volumedefined by the through cavity 12. This will, therefore, reduce thedowntime required for cleaning and maintenance of the machine.

The end 32 of the runway 30 and the outermost portion of the openpassageway 42 are arranged to provide a gradual downward transition toguide the lead onto the chute with minimal turbulence which couldotherwise result in splashing. The lead passes along 9 the downwardlycurved passageway until reaching the gap 45 which provides the outlet tothe chute 40. The wall 44 ensures a clean downwardly directed deliveryof the lead into the mould cavity 50 with any lead which overshoots thegap 45 striking the wall and being downwardly directed back through thegap 45.

Once the lead pouring has completed, the block 10 returns to its firstposition in which the through cavity is aligned with the outlet 6 oflead reservoir 4 (moving in the direction of arrows B shown in FIG. 4).In this position the reservoir is again in fluid communication with thelead supply such that the level of the reservoir will be replenished andthe through cavity 12 will be refilled. At this stage the chute 40 isretracted from its lead delivery position by being moved away from themould 50 towards the housing 2. The chute is moved by rotation of themoveable support 48 in the direction shown by arrows C, resulting in thechute 40 moving in the direction of arrows D. A cut-out 38 is providedin the lower surface of the runway 30 to accommodate the initialmovement of the chute. The cut-out is a stepped portion in the lowersurface and may for example be a slot of substantially equal width tothat of the chute.

As shown in FIG. 5, the battery plates 80 are brought into positionabove the mould 50 by a downward motion (in the direction of arrow E)until the tabs 82 of the plates lie within the mould cavity (which nowcontains molten but cooling lead). A mechanical connection is providedbetween the moveable support 48 of the chute 40 and the jig box 70 suchthat the chutes move down (as shown by arrow F) below the upper surfaceof mould 50 in conjunction with the movement of the battery plates 80towards the mould 50. This is advantageous since the chute 40 will behot (and may typically be heated to ensure the required deliverytemperature of the lead is achieved) and may help to avoid any damage tothe battery plates (or, more specifically, to the separators between thebattery plates). This arrangement may, for example, enable the height ofthe tabs 82 to be reduced and/or may eliminate the need for providing acooling air supply over the mould 50 as is known in conventionalarrangements.

Finally, as shown in FIG. 6, the battery plates 80 are moved away fromthe mould 50 by the jig box 70 (in the direction of arrow H) and ejectthe formed straps with the tabs 82. In conjunction with the movement ofthe jig box 70 the chutes 40 are moved upwards (in the direction ofarrow G) and rotated inwards (in the direction of arrow I) to return tothe delivery position.

FIG. 7 shows a mechanism 20 suitable for use in embodiments of theinvention. The mechanism comprises a drive motor 100 arranged to rotatea crank 110 which is connected via a lever arm 120 to the block 10. Itwill be noted that a plurality of blocks 10 a, 10 b and 10 c may each beconnected to a common mechanism for actuation in use. Each block 10 isassociated with a separate housing 2 a, 2 b and 2 c defining anindependent lead reservoir, each of which is in fluid communication withthe feed line 66. A simple connection may be provided between the block10 and the mechanism 20, for example a bar 21 and hook arm 22arrangement, such that the block 10 and mechanism 20 may easily bedisconnected for example to clean the block, housing or runway, or toreplace the block (for example, to provide a block with a differentcapacity through cavity 12).

In some embodiments it may be desirable to provide a plurality ofthrough cavities in a single block 210 as shown in FIG. 8. Each cavity212 a and 212 b may have a different predetermined volume depending onthe mould feature for which the lead is acquired. For example, a largermould cavity 212 a may be provided for forming a post detail while asmall mould cavity 212 b may be provided for forming a strap. Thecavities 212 a and 212 b may be suitably shaped such that their deliveryports 216 a and 216 b are of a standard profile such that nomodification is required to the chute 40.

All of the invention has been described above with reference to one ormore preferred embodiments. It will be appreciated that various changesor modifications may be made without departing from the scope of theinvention as defined in the appended claims.

For example, the skilled person will appreciate that while theembodiment above has been primarily described in relation to the formingof straps, other formations may also be cast onto the lugs of batteryplates (for example posts) and that a cast on strap machine may be usedfor the formation of any such formations without departing from thescope of the invention.

In some embodiments it may be advantageous to provide a plurality ofcavities 12 arranged to deliver lead to a single mould cavity. Forexample, this may be desirable for relatively large mould cavities. Theplurality of cavities could be in multiple blocks or in single multiplecavity block (of the type shown in FIG. 8) For example, each cavity maymeasure a separate volume of lead and the total volume of the cavitiesmay provide the volume require for the particular mould cavity. Thecavities may for example deliver to different areas of a single mouldcavity to ensure an even distribution of lead.

1. Apparatus for delivering a predetermined volume of lead to a mouldincluding: a housing defining a lead reservoir having a lead outletdefined in its base and in communication with the reservoir; a runwaybeneath the base, spaced from the base and generally parallel thereto; ablock slidably mounted between the base and the runway and defining athrough cavity having the predetermined volume for receiving lead fromthe outlet in a first position and for releasing the lead in a secondposition; and a mechanism for reciprocating the block between the firstand second positions.
 2. Apparatus as claimed in claim 1 wherein thecavity has an upper inlet alignable with the lead outlet in the firstposition and a lower deliver port which can deliver lead in the secondposition.
 3. Apparatus as claimed in claim 2 wherein the runway stopsshort of or has an opening at the second position.
 4. Apparatus asclaimed in claim 1 wherein the housing defines a bleed opening alignedwith the second position for allowing the ingress of gas to the upperpart of the cavity.
 5. Apparatus as claimed in claim 1 wherein thehousing is provided with a cover to define an enclosed ullage above thereservoir and wherein the housing further includes an inlet for theprovision of an inert gas to the ullage.
 6. Apparatus as claimed inclaim 1 wherein the block includes a through hole for connecting thereservoir to a lead supply where the block is in the first position. 7.Apparatus as claimed in claim 1 further including a drive mechanism forreciprocating the block.
 8. Apparatus as claimed in claim 1 whereinfacing surfaces of the block and the reservoir form a seal therebetween.9. Apparatus as claimed in claim 1 wherein facing surfaces of the blockand runway form a seal.
 10. Apparatus as claimed in claim 1 including aconstant head lead supply for supplying lead to the reservoir. 11.Apparatus as claimed in claim 1 further including a chute defining alead passageway for extending between the second position and a mouldfill position.
 12. Apparatus as claimed in claim 11 wherein thepassageway includes a channel and a gap at the delivery position and thechute further includes a wall on the opposite side of the gap to thechannel for directing lead downwardly as it debouches from the channel.13. Apparatus as claimed in claim 12 wherein the channel is an openchannel.
 14. Apparatus as claimed in claim 11 including a movablesupport for supporting the chute for movement between a lead deliveryposition and a rest position.
 15. Apparatus as claimed in claim 11further including a carriage for the chute for moving the chute betweena lead delivery position and a store position.
 16. Apparatus as claimedin claim 1 wherein the block comprises a plurality of through cavitieseach arranged for delivering a predetermined volume of lead to adifferent section of a mould.
 17. Apparatus as claimed in claim 1wherein the runway further comprises blind hole which is aligned withthe cavity when the block is in the first position.
 18. Lead deliveryapparatus including a plurality of apparatuses as claimed in claim 1.19. Lead delivery apparatus as claimed in claim 18 wherein at least apair of blocks are linked together to reciprocate together.
 20. A caston strap machine including a mould comprising a mould block defining aplurality of mould recesses and an apparatus as claimed in claim 1 fordelivering a predetermined volume of lead for each recess.
 21. A machineas claimed in claim 20 wherein at least a pair of blocks are linkedtogether to reciprocate together.
 22. A lead delivery apparatuscomprising a delivery chute which, in use, defines a passageway betweena lead delivery device and a mould, wherein the chute is moveablebetween a lead delivery position in which at least a portion of thechute is positioned over the mould and a store position, in which thechute does not overlie the mould.
 23. An apparatus as claimed in claim22, wherein the store position is below the plane of the upper mouldsurface.
 24. An apparatus as claimed in claim 22 wherein the chute ismoved across the surface of the mould before being displaced in adirection which is substantially perpendicular to the plane of the mouldsurface.
 25. An apparatus according to any of claims 22 wherein at leastpart of the movement of the chute is linked to the movement of a jig boxwhich is arranged, in use, to bring a part into contact with the lead inthe mould.